KR20150137888A - Composite cathode active material, preparation method thereof, and lithium battery comprising the same - Google Patents

Abstract

Disclosed are a composite positive electrode active material comprising: a core active material; one or more first polymers selected from the polymers of a fully fluorinated polymer formed on at least part of the core active material and a polymer having 60 to 90 atomic percent of a fluorine content; and a coating film including a carbon nano structure, a producing method thereof, a positive electrode comprising the composite positive electrode active material, and a lithium battery comprising the positive electrode.

Description

TECHNICAL FIELD The present invention relates to a composite cathode active material, a method of manufacturing the same, and a lithium battery including the composite cathode active material,

Complex cathode active material, method for manufacturing the same, and lithium battery including the same

As various devices become smaller and higher in performance, there is a demand for lithium batteries which are miniaturized, lightweight, and high energy density used in such devices.

In order to realize a lithium battery having the above-described characteristics, researches have been actively made on the development of a cathode active material having a high voltage and excellent high-rate characteristics and life characteristics.

Conventional high-voltage positive electrode active materials cause side reactions with the electrolyte during charging and discharging, and by-products such as transition metals and gases eluted from the positive electrode active material are produced. Such side reactions of the cathode active material and by-products generated from the cathode active material deteriorate performance such as high-rate characteristics and life characteristics of the battery. Therefore, there is a high demand for development of a cathode active material having improved lifetime and high-rate characteristics at such a high voltage.

An aspect of the present invention is to provide a novel composite cathode active material and a method of manufacturing the same.

Another aspect is to provide a lithium battery including the composite cathode active material.

According to one aspect,

Core active material;

At least one first polymer selected from a fully fluorinated polymer formed on at least a portion of the core active material and a polymer having a fluorine content of 60 to 90 at%; And

There is provided a composite cathode active material containing a coating film containing a carbon nanostructure.

According to other aspects

At least one polymer selected from a completely fluorinated polymer and a polymer having a fluorine content of 60 to 90 atomic% on the core active material; And forming a coating film containing the carbon nanostructure. The present invention also provides a method for producing a composite cathode active material.

According to another aspect

There is provided a lithium battery including the above-described anode.

The composite cathode active material according to one aspect includes a core active material; And a coating film including a completely fluorinated polymer and a carbon nanostructure formed on at least a portion of the core active material, thereby improving the high-rate characteristics and lifetime characteristics of the lithium battery.

1 is a view showing a structure of a composite cathode active material according to one embodiment.
2 is an exploded perspective view of a lithium battery according to one embodiment.
3A, 4A, 5A, and 6A are electron micrographs of the composite cathode active material of Production Example 1 and the cathode active material of Comparative Production Example 1-3, respectively.
Figs. 3B, 4B, 5B and 6B are electron micrographs of the photographs of Figs. 3A, 4A, 5A and 6A magnified at a high magnification.
7 is an electron micrograph of polytetrafluoroethylene (PTFE).
FIGS. 8A and 8B show SEM-EDS analysis results of the composite cathode active material obtained according to Production Example 1 by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS).
FIGS. 9A and 9B show electron microscopic-focused ion beam analysis results of the cross section and the surface of the composite cathode active material obtained according to Production Example 1. FIG.
10 shows the result of thermogravimetric analysis of the cathode active material of Comparative Production Example 1-2 and the composite cathode active material of Production Example 1.
11 shows XPS analysis results of the composite cathode active material of Production Example 1 and the cathode active material of Comparative Production Example 1-3.
FIG. 12 shows the capacity retention rate change for the coin cell manufactured according to Example 1 and Comparative Example 1-4.
Fig. 13 shows non-capacity characteristics of a coin cell manufactured according to Example 1 and Comparative Example 1-4.
FIG. 14 shows T-peel test results for the positive electrode obtained in Example 1 and Comparative Example 1. FIG.

Hereinafter, a composite cathode active material according to one embodiment, a lithium battery including the same, and a method of manufacturing the same will be described in detail.

Core active material; At least one first polymer selected from a completely fluorinated polymer formed on at least a part of the core active material and a polymer having a fluorine content of 60 to 90 at%; And a coating film containing a carbon nanostructure.

The core active material includes a material capable of intercalating lithium.

The content of the first polymer is 10 to 700 parts by weight, for example, 20 to 500 parts by weight, based on 100 parts by weight of the carbon nanostructure. When the content of the first polymer is within the above range, the life and the high-rate characteristics of the lithium battery manufactured using the composite cathode active material are excellent.

The total content of the first polymer and the carbon nanostructure is 0.1 to 30 parts by weight, for example, 0.1 to 10 parts by weight, specifically 0.5 to 4 parts by weight, based on 100 parts by weight of the composite cathode active material. When the content of the first polymer and the carbon nanostructure is within the above range, a composite lithium battery can be used to manufacture a lithium battery having excellent life characteristics and rate characteristics.

The coating film may have a continuous coating film shape formed on at least a part of the core active material, for example, continuously formed over the entire surface of the core active material, or may have an island shape formed on a part of the surface of the core active material .

The fully fluorinated polymer is a polymeric hydrocarbon compound in which all of the hydrogen atoms are substituted with fluorine, for example, polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer (PFA), polytetrafluoroethylene-hexafluoro Poly (tetrafluoroethylene-co-hexafluoropropylene) (FEP) copolymer, and polytetrafluoroethylene-perfluoroalkyl methacrylic copolymers.

The fluorine content may be 60 to 90 atomic%, for example, 65 to 80 atomic% in the whole elements of the polymer compound. When the content of fluorine is within the above range, the effect of fluorine is excellent.

The fluorine content in the first polymer can be determined by X-ray photoelectron spectroscopy (XPS), elemental analysis (EA), thermal analysis (TGA) or scanning electron microscopy-X-ray spectroscopy (SEM-EDS) Polymers have high binding energy and high chemical stability to acids or alkalis. Therefore, when a coating film using such a first polymer is formed on the surface of the core active material, stability against a substance such as hydrogen fluoride (HF) formed due to decomposition of an electrolyte in a battery system is excellent. The life characteristics of the battery can be improved by using the anode using the composite cathode active material.

According to one embodiment, the first polymer may further include a second polymer as needed. Examples of the second polymer include polyvinylidene fluoride, polyimide, polyethylene, polyester, polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene (PTFE), carboxymethylcellulose-styrene Carboxymethyl cellulose-styrene-butadiene rubber (SMC / SBR) copolymer, styrene-butadiene rubber-based polymer, and the like.

The content of the second polymer is, for example, 0.1 to 20 parts by weight, for example, 1 to 10 parts by weight, based on 100 parts by weight of the first polymer.

In the composite cathode active material according to one embodiment, the polymer or composite cathode active material contained in the coating film has a solubility in an organic solvent of 0.1 mg / ml or less, for example, 0.00001 to 0.1 mg / ml. Examples of the organic solvent include N-methylpyrrolidone (NMP).

The carbon nanostructure is excellent in conductivity, and a composite cathode active material capable of improving the speed characteristics of the battery can be obtained by forming a coating film on the surface of the core active material. By thus having a coating film containing the polymer and the carbon nanostructure, the speed and lifetime characteristics of a lithium battery employing a positive electrode using a composite positive electrode active material can be improved.

The coating film of the composite cathode active material may have a single film structure including the polymer and the carbon nanostructure. Or the coating film may be formed in the form of a multilayer film. For example, the coating layer may include a first coating layer formed on the core active material and containing at least one first polymer selected from a completely fluorinated polymer and a polymer having a fluorine content of 60 to 90 atomic%, and a carbon nanostructure Layer structure in which a second coating film is formed. The use of the composite cathode active material having such a two-layered coating film can improve the speed and life characteristics of the battery.

The thickness of the coating film is not particularly limited to a thickness within a range for increasing the capacity and efficiency of the battery, but may be 1 to 200 nm, for example, 30 nm to 200 nm. When the thickness range of the coating film is in the above range, a battery having excellent charge / discharge rate characteristics and life characteristics can be obtained.

In the composite cathode active material, the carbon nanostructure may include, for example, a single-walled carbon nanotube, a multi-walled carbon nanotube, or a combination thereof. For example, the average aspect ratio of the carbon nanotubes (CNTs) may be about 300 or less, for example, about 250 or less, specifically about 50 to 200.

The "average aspect ratio" was defined as "average length / average diameter ratio" and the "average diameter" was obtained by observing 10 or more carbon nanotubes using a scanning electron microscope (SEM) The "average length" is an average value of values obtained by measuring lengths of 10 or more carbon nanotubes using a scanning electron microscope (SEM).

The carbon nanotubes may have an average diameter of, for example, 1 nm to 50 nm, and may be, for example, 2 nm to 50 nm. Carbon nanotubes having an average diameter within the above range can be uniformly disposed on the core active material, thereby improving electrical conductivity and improving charge / discharge rate characteristics.

The CNT can selectively pass activation treatment. Here, the activation treatment refers to, for example, treating commercially available CNTs with at least one selected from among nitric acid, an acid such as sulfuric acid, and an oxidizing agent such as potassium permanganate, and performing ultrasonic treatment. When the activation treatment is performed, the conductivity of the CNT can be further improved.

1 is a schematic view of a composite cathode active material 10 according to one embodiment.

1, the composite cathode active material includes a carbon nanotube 11 and a fully fluorinated polymer and a polymer having a fluorine content of 60 to 90 atomic% 1 < / RTI > polymer (12). In FIG. 1, the coating film 13 has a continuous film shape on the core active material 10. However, in some cases, the coating film may have a discontinuous film form, for example an island form.

The carbon nanostructure CNT in the coating layer may be embedded in the coating layer 13 or partially exposed from the coating layer 13 as shown in FIG.

In the coating film, a part of the carbon nanostructure may be melted and amorphized.

This composite cathode active material can effectively prevent direct contact between the electrolyte and the core active material. As a result, the decomposition of the anode due to the oxidation reaction of the electrolyte can be suppressed. As the charge and discharge cycles are repeated, the increase in the interfacial resistance between the anode and the electrolyte can be reduced to improve the charging / discharging rate characteristics and the life characteristics.

The thickness of the coating film may be 1 to 200 nm. For example, the thickness of the coating film may be 30 nm to 200 nm. The composite cathode active material containing the coating film within the above range can minimize the resistance difference between the interface of the composite oxide core and the coating film interface, at which lithium can be intercalated and deintercalated.

The core active material is a compound capable of intercalation / deintercalation of lithium, and can be used as a cathode active material at a high voltage of 4.2 V or higher, for example, in the range of 4.3 to 5.5 V

Layered or spinel-type structure. The core active material may be selected from, for example, overlithiated layered oxides, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide doped with a nonmetallic element, lithium nickel manganese oxide doped with a non- Lithium nickel cobalt manganese oxide doped with a non-metallic element, and combinations thereof.

For example, the core active material may be a compound represented by the following general formula (1).

[Chemical Formula 1]

_{yLi [Li 1/3 Me 2} /3] O 2 - (1-y) LiMe'O 2

Me is at least one selected from the group consisting of Mn, Mo, W, V, Ti, Zr, Ru, Rh, Pd, Os, Ir and Pt. At least one selected from the group consisting of Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg and boron.

In the above formula (1), 0 < y <

In the above formula (1), Me may be represented by the following formula (2).

(2)

M ' _a M _b Mn _c

M in Formula 2 may be at least one selected from the group consisting of molybdenum (Mo), tungsten (W), vanadium (V), titanium (Ti), zirconium (Zr), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium , Iridium (Ir), and platinum (Pt).

M 'is at least one selected from the group consisting of Ni, Cu, Zn, Co, Cr, Fe and Mg,

0? A? 0.33, 0 <b? 0.33, and a + b + c = 1.

The core active material is at least one selected from the compounds represented by the following general formulas (3) to (6).

(3)

Li _x Co _{1 - y - z} Ni _y M _z O _{2 - a} X _a

0.9? X? 1.6, 0? Y? 1, 0? Z? 1, 0? A?

X is at least one selected from oxygen (O), fluorine (F), sulfur (S) and phosphorus (P)

M is at least one selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg,

[Chemical Formula 4]

Li _x Mn _{2 - y} M _y O _{4 - a} X _a

X? 1.6, 0? Y? 1, 0? Z? 0.5, 0? A? 1,

X is at least one selected from oxygen (O), fluorine (F), sulfur (S) and phosphorus (P)

M is at least one selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg,

[Chemical Formula 5]

MFePO ₄

In Formula 5, M is at least one selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg and boron.

(6)

Li _x M _y M ' _z PO _{4 - d} X _d

0.9? X? 1.1, 0? Y? 1, 0? Z? 1, 1.9? X + y + z? 2.1, 0? D? M is at least one selected from the group consisting of Fe, Mn, Ni and Co;

M 'is composed of Mg, Ca, Sr, Ba, Ti, Zr, Nb, Mo, W, Zn, Al, Si, Cr, Zr, Nb, Cu, V, Ti, Zn, Ga, At least one selected from the group; X is at least one selected from the group consisting of S and F.

In the above formulas (3) and (4), x is 1.1 to 1.6. Core active material according to an embodiment, the _{Li 1.18 Ni 0.17 Co 0.1 Mn 0.56} O 2, LiCoO 2, LiFePO 4, LiFe 1 -a Mn a PO 4 (0 <a <1), LiNi 0 .5 Mn 1 .5 O is ₄ or LiMnPO _4.

When a high capacity positive electrode active material containing a large amount of lithium as a core active material is used, charging and discharging are required under a high voltage and the electrolyte is likely to be decomposed on the surface of the positive electrode. As a result, a transition metal such as Mn contained in the lithium transition metal oxide Is dissolved by the electrolyte and is liable to elute. Also, when the cycle progresses due to the surface side reaction or when the capacity is reduced and stored at high temperature charging / discharging, self-discharge is likely to occur.

However, by preventing the decomposition between the core active material and the electrolyte even under a high voltage and / or a high temperature by using a composite cathode active material containing a coating film according to one embodiment, the charging / discharging speed characteristics and lifetime characteristics of the lithium battery can be improved.

At least one first polymer selected from a completely fluorinated polymer and a polymer having a fluorine content of 60 to 90 atomic% on the core active material according to another aspect; And forming a coating film containing the carbon nanostructure. The present invention also provides a method for producing a composite cathode active material.

The step of forming the coating film may be carried out according to a dry method. Here, the dry method includes all the methods of forming a coating film on the surface of the core active material by applying mechanical energy to the core active material, the first polymer, and the carbon nanostructure without using a solvent.

The drying method includes, for example, a ball mill method, a hybridization method, or a mechanofusion method. Here, the ball mill method is, for example, a planetary ball mill method, a low speed ball mill method, or a high speed ball mill method.

In the mechanofusion method, the mixture is put into a rotating container, and then the mixture is fixed to the inner wall of the container by centrifugal force, and then compressed into a gap between the inner wall of the container and the adjacent arm head at a slight interval.

When carrying out according to the above-mentioned dry method, the heat treatment step is not performed. If necessary, a heat treatment step may be performed within a range in which the first polymer is not denatured after the coating film is formed. When the heat treatment is performed, the adhesion of the coating film to the core active material is improved, and impurities are removed, thereby forming a firm coating film on the core.

In some cases, a coating film can be formed according to a wet method.

The wet method may be a spray method, a coprecipitation method, or a dipping method. For example, a dipping method can be used.

The dipping method is, for example, preparing a dispersion in which carbon nanostructure powder and core active material are dispersed in an organic solvent such as acetone or an alcohol such as methanol, ethanol or NMP. The core active material is immersed in the dispersion and then heat-treated.

A lithium battery according to another aspect includes: a positive electrode; Electrolyte; And a cathode, and the anode may include the composite cathode active material described above. The lithium battery can be manufactured, for example, as follows.

First, the anode can be manufactured as follows.

The composite cathode active material according to one embodiment, the conductive agent, the binder and the solvent are mixed to prepare a composition for forming the cathode active material layer.

The composition for forming the positive electrode active material layer may be directly coated on the current collector and dried to prepare a positive electrode plate having the positive electrode active material layer.

Alternatively, the composition for forming a cathode active material layer may be cast on a separate support, and a film obtained by peeling the support from the support may be laminated on the current collector to produce a cathode having the cathode active material layer formed thereon.

The anode is operable at a high voltage of 4.2V or higher, for example 4.3 to 5.5V.

Examples of the conductive agent of the composition for forming a positive electrode active material layer include carbon black, graphite fine particle natural graphite, artificial graphite, acetylene black, ketjen black, carbon fiber; Metal powders or metal fibers or metal tubes such as carbon nanotubes, copper, nickel, aluminum, and silver; Conductive polymers such as polyphenylene derivatives, and the like can be used, but the present invention is not limited thereto, and any conductive polymer may be used as the conductive polymer in the art.

Examples of the binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyimide, polyethylene, polyester, polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene (PTFE) A carboxymethyl cellulose-styrene-butadiene rubber (SMC / SBR) copolymer, a styrene butadiene rubber-based polymer, or a mixture thereof may be used.

As the solvent, N-methylpyrrolidone, acetone, water or the like may be used, but not limited thereto, and any solvent which can be used in the technical field can be used.

The content of the composite cathode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium battery.

The positive electrode active material may further include a first positive electrode active material conventionally used in a lithium battery in addition to the composite positive electrode active material described above. The content of the first cathode active material is, for example, 0.1 to 30 parts by weight based on 100 parts by weight of the composite cathode active material.

The first positive electrode active material may include at least one selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide, but is not limited thereto. Any cathode active material available in the art may be used.

For example, Li _a A _{1 - b} B _b D ₂ , where 0.90? A? 1.8, and 0? B? 0.5; Li _a E _{1 -b} B _b O _{2 -c} D _c wherein, in the formula, 0.90? A? 1.8, 0? B? 0.5, 0 _{? C?} 0.05; LiE _{2 - b} B _b O _{4 - c} D _{c where} 0? B? 0.5, 0 _{? C?} 0.05; Li _a Ni _{1 -b- c} Co _b B _c D _? Wherein, in the formula, 0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c D _? Wherein, in the formula, 0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _b E _c G _d O ₂ wherein 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, and 0.001? D? 0.1; Li _a Ni _b Co _c Mn _d GeO ₂ wherein 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, 0? D? 0.5, and 0.001? E? 0.1. Li _a NiG _b O ₂ (in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1); Li _a CoG _b O ₂ (in the above formula, 0.90? A? 1.8, 0.001? B? 0.1); Li _a MnG _b O ₂ (in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ (in the above formula, 0.90? A? 1.8, 0.001? B? 0.1); QO _2; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO _4; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 _{? F? 2} ); _{(0≤f≤2) Li (3-f} ) Fe 2 (PO 4) 3; A compound represented by any one of the formulas of LiFePO ₄ can be used.

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

The content of the composite cathode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium battery. At least one of the conductive agent, the binder and the solvent may be omitted depending on the use and configuration of the lithium battery.

The negative electrode can be obtained by substantially the same method except that the positive electrode active material is replaced with the negative electrode active material in the positive electrode manufacturing process.

As the negative electrode active material, a carbon-based material, silicon, a silicon oxide, a silicon-based alloy, a silicon-carbon-based material composite, a tin, a tin alloy, a tin-carbon composite or a metal oxide or a combination thereof is used.

The carbon-based material may be crystalline carbon, amorphous carbon or a mixture thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite in the form of amorphous, plate-like, flake, spherical or fibrous type, and the amorphous carbon may be soft carbon or hard carbon carbon fiber, carbon fiber, mesophase pitch carbide, fired coke, graphene, carbon black, fullerene soot, carbon nanotube, and carbon fiber, Anything that can be used is possible.

The negative electrode active material may be selected from the group consisting of Si, SiOx (0 <x <2, for example, 0.5 to 1.5), Sn, SnO ₂ or a silicon-containing metal alloy and mixtures thereof. At least one of Al, Sn, Ag, Fe, Bi, Mg, Zn, In, Ge, Pb and Ti may be used as the metal for forming the silicon alloy.

The negative electrode active material may include a metal / metalloid alloy that is alloyable with lithium, an alloy thereof, or an oxide thereof. For example, the metal / metalloid capable of alloying with lithium may be at least one selected from the group consisting of Si, Sn, Al, Ge, Pb, Bi, SbSi-Y alloy (Y is an alkali metal, an alkaline earth metal, a Group 13 element, , A rare earth element or a combination element thereof and not Si), an Sn-Y alloy (Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, , MnOx (0 < x? 2), and the like. The element Y may be at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Se, Te, Po, or a combination thereof. For example, the oxide of the metal / metalloid capable of alloying with lithium may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO ₂ , SiO _x (0 <x <2) and the like.

For example, the negative electrode active material may include one or more elements selected from the group consisting of Group 13 elements, Group 14 elements, and Group 15 elements of the Periodic Table of the Elements.

For example, the negative electrode active material may include at least one element selected from the group consisting of Si, Ge, and Sn.

The content of the negative electrode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium battery.

The separator is interposed between the positive electrode and the negative electrode, and an insulating thin film having high ion permeability and mechanical strength is used.

The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 20 mu m. As such a separator, for example, an olefin-based polymer such as polypropylene; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid polymer electrolyte is used as the electrolyte, the solid polymer electrolyte may also serve as a separator.

Among the separators, specific examples of the olefin-based polymer include polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more thereof. The separator may be a polyethylene / polypropylene double layer separator, a polyethylene / polypropylene / polyethylene triple layer separator, A multi-layered film such as a polypropylene / polyethylene / polypropylene three-layer separator or the like may be used.

The lithium salt-containing nonaqueous electrolyte is composed of a nonaqueous electrolyte and a lithium salt.

As the non-aqueous electrolyte, a non-aqueous electrolyte, an organic solid electrolyte, or an inorganic solid electrolyte is used.

The nonaqueous electrolytic solution includes an organic oil. These organic solvents may be used as long as they can be used as organic solvents in the art. Examples of the solvent include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate N, N-dimethylformamide, N, N-dimethylformamide, tetrahydrofuran, tetrahydrofuran, Dimethylacetamide, N, N-dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether or mixtures thereof.

Examples of the organic solid electrolyte include a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, a polyelectrolytic lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene chloride, And the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ -LiI- ₃ PO ₄ -Li ₂ S-SiS _2, and the like can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for _{example, LiPF 6, LiBF 4, LiSbF} 6, LiAsF 6, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, LiC ₄ F ₉ SO ₃ , LiAlO ₂ , LiAlCl ₄ , LiN (C _x F _{2 x +1} SO ₂ ) (C _y F _{2y + 1} SO ₂ ) (where x and y are natural numbers), LiCl, LiI, . For the purpose of improving the charge-discharge characteristics and the flame retardancy, non-aqueous electrolytes include, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, hexamethylphosphoamide hexamethyl phosphoramide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxyethanol, Etc. may be added. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability.

2, the lithium battery 20 includes an anode 23, a cathode 22, and a separator 24. The positive electrode 23, the negative electrode 22 and the separator 24 described above are wound or folded and accommodated in the battery case 26. Then, an organic electrolytic solution is injected into the battery case 26 and sealed with a cap assembly 25 to complete the lithium battery 21. The battery case may have a cylindrical shape, a rectangular shape, a thin film shape, or the like. For example, the lithium battery may be a thin film battery. The lithium battery may be a lithium ion battery.

A separator may be disposed between the anode and the cathode to form a battery structure. The cell structure is laminated in a bi-cell structure, then impregnated with an organic electrolyte solution, and the obtained result is received in a pouch and sealed to complete a lithium ion polymer battery.

In addition, a plurality of battery assemblies may be stacked to form a battery pack, and such battery pack may be used for all devices requiring high capacity and high output. For example, a notebook, a smart phone, an electric vehicle, and the like.

The lithium battery can exhibit excellent cycle charge / discharge efficiency and capacity by improving the conductivity. In addition, the resistance according to the charge / discharge rate can be reduced, high-speed charge / discharge can be realized, side reactions at the surface of the electrode can be suppressed during charging and discharging, electrolyte decomposition at the surface of the anode can be effectively prevented, and battery life is prolonged. As such, it is suitable for an electric vehicle (EV) because it has a high rate characteristic and a good life characteristic. For example, a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV).

Hereinafter, specific embodiments will be described. It should be understood, however, that the embodiments described below are intended to be illustrative or for the purpose of illustration only and are not intended to be limiting.

Manufacturing example  1: Preparation of composite cathode active material

Active material core of _{Li 1 .18 Ni 0 .17 Co 0} .1 Mn 0 .56 O 2 100 parts by weight of single wall carbon nanotubes (enanotec Co., purity: 90% or more, average particle diameter: 2 nm, average length: 30 μm) and 0.5 part by weight of polytetrafluoroethylene were mixed and pulverized at about 3000 rpm for 30 minutes using Nobilta NOB-MINI (manufactured by Hosokawa) for 30 minutes to form the single wall carbon nanotubes and the single wall carbon nanotubes A composite cathode active material including a coating film of polytetrafluoroethylene was prepared.

In the composite cathode active material obtained above, the content of CNT was 1 part by weight, the content of polytetrafluoroethylene was 0.5 parts by weight, and the content of OLO as a core active material was 98.5 parts by weight.

Manufacturing example  2-4: Preparation of composite cathode active material

A composite cathode active material was prepared in the same manner as in Production Example 1 except that the content of polytetrafluoroethylene was changed to 0.2 weight, 1 weight part and 5 weight parts instead of 0.5 weight part, respectively.

Comparative Preparation Example 1 : Cathode active material

As a cathode active material was used as _{Li 1 .18 Ni 0 .17 Co 0} .1 Mn 0 .56 O 2.

Comparative Manufacturing Example  2: Preparation of cathode active material

The cathode active material was prepared in the same manner as in Production Example 1 except that single-walled carbon nanotubes were not used.

Comparative Manufacturing Example  3: Preparation of cathode active material

A cathode active material was prepared in the same manner as in Production Example 1, except that the content of polytetrafluoroethylene was changed to 1 part by weight instead of 0.5 part by weight without using single-wall carbon nanotubes.

Comparative Manufacturing Example  4: Preparation of cathode active material

Except that polytetrafluoroethylene was not used and 1 part by weight of single-walled carbon nanotubes were used in place of polytetrafluoroethylene, to prepare a cathode active material.

Example  1: anode and Coin cell  Produce

A mixture obtained by mixing the composite cathode active material prepared in Example 1, a carbon conductive agent (Denka Black), and polyvinylidene fluoride (PVdF) in a weight ratio of 92: 4: 4 was dissolved in N-methylpyrrolidone (NMP) Were mixed together in agate mortar to prepare a slurry. The slurry was bar coated on an aluminum current collector having a thickness of 15 μm, dried at room temperature, dried again under vacuum at 120 ° C., and rolled and punched to prepare a positive electrode having a thickness of 55 μm.

Using the positive electrode, lithium metal was used as a counter electrode, and a PTFE separator and 1.3M LiPF ₆ were mixed in a ratio of EC (ethylene carbonate) + DEC (diethyl carbonate) + EMC (ethyl methyl carbonate) Volume ratio) was used as an electrolyte to prepare a coin cell.

Example  2-4: anode and Coin cell  Produce

A positive electrode plate and a coin cell were fabricated in the same manner as in Example 1, except that the composite positive electrode active material prepared in Example 2-4 was used in place of the composite positive electrode active material prepared in Example 1.

Comparative Example  1-4: anode and Coin cell  Produce

A positive electrode and a coin cell were fabricated in the same manner as in Example 1, except that the positive electrode active material prepared in Comparative Example 1-4 was used in place of the composite positive electrode active material prepared in Example 1.

Comparative Example  5: anode and Coin cell  Produce

The positive electrode active material _{Li 1 .18 Ni 0 .17 Co 0} .1 Mn 0 .56 O 2, single wall carbon nanotubes (enanotec Co., purity: 90% or more, average particle diameter: 2 nm, average length: 30 um) , And polytetrafluoroethylene in a weight ratio of 92: 4: 4 was mixed with N-methyl pyrrolidone (NMP) in an agate mortar to prepare a slurry. The slurry was bar coated on an aluminum current collector having a thickness of 15 μm, dried at room temperature, dried again under vacuum at 120 ° C., and rolled and punched to prepare a positive electrode having a thickness of 55 μm.

Using the positive electrode, lithium metal was used as a counter electrode, and a PTFE separator and 1.3M LiPF ₆ were mixed in a ratio of EC (ethylene carbonate) + DEC (diethyl carbonate) + EMC (ethyl methyl carbonate) Volume ratio) was used as an electrolyte to prepare a coin cell.

Evaluation example  1: scanning electron microscope SEM ) analysis

Electron microscope analysis of the cathode active material of Comparative Production Example 1, the cathode active materials of Comparative Production Examples 2 and 3, and the cathode active material obtained according to Production Example 1 were carried out. The scanning electron microscope analysis was observed using a scanning electron microscope (SEM, product of Hitachi, model: S-5500), as shown in Figs. 3A to 6A, respectively. And Figs. 3B to 6B are enlarged views of Figs. 3A to 6A, respectively. An electron micrograph of polytetrafluoroethylene is shown in Fig. 7 for comparison with the cathode active material obtained according to Production Example 1. Fig.

As a result, it was found that PTO and CNT were coated on the OLO surface.

Evaluation example  2: scanning electron microscope scanning electron microscope : SEM ) - Energy dispersive spectroscopy ( Energy dispersive spectroscopy : EDS )

The composite cathode active material obtained according to Preparation Example 1 was analyzed using an electron microscope. The results of the analysis are shown in FIG. 8A, and the SEM-EDS results for fluorine in the square display area of FIG. 8A are shown in FIG. 8B.

As a result, it can be seen that PTFE is uniformly coated on the surface of the core active material.

Evaluation example  3 :  Electron microscope SEM ) - Focused ion beam ( FIB : Focusing Ion Beam ) analysis

The cross section and the surface of the composite cathode active material obtained according to Production Example 1 were subjected to an electron scanning microscope-focused ion beam analysis. The cross-sectional and surface analysis results of the composite cathode active material are shown in FIGS. 9A and 9B, respectively.

Referring to this, it was confirmed that a coating film was formed on the surface of the core active material.

Evaluation example  4: Thermal weight  analysis( Thermogravimetry Analysis ; TGA )

Thermogravimetric analysis of the positive electrode active material of Comparative Production Example 1-2 and the composite positive electrode active material of Production Example 1 was performed using a thermogravimetric analyzer (TA instrument, SDF-2960).

The results of the analysis are shown in FIG.

Referring to FIG. 10, the content range of PTFE and CNT present in the composite cathode active material of Production Example 1 was confirmed.

Evaluation example  5: X-ray photoelectron spectroscopy ( XPS ) analysis

The composite cathode active material of Production Example 1 and the cathode active material of Comparative Production Example 1-3 were subjected to XPS analysis under the following conditions.

The sample was dried under vacuum at 100 ° C. for 4 hours. Quantum 2000 Scanning ESCAM microprobe (manufactured by Physical Electronics Co., Ltd.) was used as an XPS analyzer. Monochromated Al-Kα line (1486.6 eV, 27.7 W) was used as an X-ray source Respectively.

The results of the analysis are shown in Table 1 and Fig.

division Content (atm%) C1s O1s F1s Na1s Mn2p Co2P Ni2P Production Example 1 49.31 23.13 16.07 2.16 5.8 0.67 2.87 Comparative Preparation Example 1 10.74 53.77 0 6.18 16.81 2.99 9.51 Comparative Production Example 2 15.2 52.99 4.72 3.63 16.44 2.28 4.76 Comparative Production Example 3 15.63 52.95 6.44 4.04 14.66 1.6 4.69

Referring to Table 1, when a coating film containing CNT and PTFE was formed according to Production Example 1, a change in the fluorine bonding state was observed as compared with Comparative Production Example 2. According to Production Example 1, the content of fluorine against C1s and F1s against C1s was higher than that of Comparative Production Example 1. From this, it can be seen that PTFE and CNT coating films are formed on the surface of the core active material.

Evaluation example  6: Evaluation of life characteristics

1) Example 1 and Comparative Example 1-4

The coin cells prepared according to Example 1 and Comparative Example 1-4 were charged and discharged 120 times at a constant current of 1 C rate in a voltage range of 2.5 to 4.6 V relative to lithium metal at a high temperature of 45 ° C. The capacity retention rate in the 120th cycle is expressed by the following equation (1). A part of the capacity retention rate in the 120th cycle is shown in Fig.

[Equation 1]

Capacity retention rate in 120 ^th cycle [%] = [Discharge capacity in 120th cycle / 1 ^st Discharge capacity in cycle] × 100

As shown in FIG. 12, the coin cell of Example 1 exhibited improved life characteristics compared to the coin cell of Comparative Example 1-4.

2) Example 1 and Comparative Example 5

As in the method for evaluating the life characteristics of the above-described Example 1 and Comparative Example 1-4,

And the life characteristics of the coin cell of Comparative Example 5 were evaluated.

As a result of the evaluation, it was found that the life characteristics of the coin cell of Example 1 were improved as compared with the case of Comparative Example 5.

Evaluation example  8: Rate  Performance( rate capability )

1) Example 1 and Comparative Example 1-4

The coin cells prepared according to Example 1 and Comparative Example 1-4 were charged at a constant current (0.5 C) and a constant voltage (4.5 V, 0.05 C cut-off) at room temperature (25 ° C.) ). Then, the magnitude of the electric current was discharged to 2.5 V under a constant current (0.2 C or 2 C) condition. That is, the rate capability of the coin cell was evaluated by changing the discharge rates to 0.2C and 2C, respectively. The results are shown in Table 2. C-rate is the discharge rate of the cell, which is the value obtained by dividing the total capacity of the cell by the total discharge time. In the following Table 3, the rate-limiting performance is obtained by the following equation (2) and the voltage reduction is obtained by the equation (3).

&Quot; (2) &quot;

Rate performance (%) = [(Discharge capacity at 2C) / (Discharge capacity at 0.2C)] x 100

&Quot; (3) &quot;

Voltage attenuation = (discharge voltage in the 100th cycle, discharge voltage in the second cycle)

division Rate performance (%) Voltage attenuation
(V) Example 1 79.6 0.142 Comparative Example 1 72.8 0.16 Comparative Example 2 69.4 0.145 Comparative Example 3 67.5 0.142 Comparative Example 4 81.3 0.17

Referring to Table 3, the coin cell manufactured according to Comparative Example 4 uses a cathode active material having a CNT coating layer to improve the rate-limiting performance but has a large voltage drop.

On the other hand, in the coin cell manufactured according to Example 1, the delay effect of the voltage attenuation was improved as compared with the case of Comparative Example 1-4 by employing the electrode using the composite cathode active material having the coating film containing PTFE and CNT, The CNT of CNTs showed that the rate - limiting performance was improved.

2) Examples 1-4 and Comparative Example 1

The coin cell prepared in Example 1-4 and Comparative Example 1 was charged at a constant current (0.5 C) and a constant voltage (4.5 V, 0.05 C cut-off) at room temperature (25 ° C.) ). Then, the magnitude of the electric current was discharged to 2.5 V under a constant current (0.2 C or 2 C) condition. That is, the rate capability of the coin cell was evaluated by changing the discharge rates to 0.2C and 2C, respectively. The results are shown in Table 3. C-rate is a discharge rate of the cell, which means a value obtained by dividing the total capacity of the cell by the total discharge time. The rate-limiting performance in the following Table 3 is obtained by the following equation (4).

&Quot; (4) &quot;

Rate performance (%) = [(Discharge capacity at 2C) / (Discharge capacity at 0.2C)] x 100

division Rate performance (%) Example 1 81.2 Example 2 79.6 Example 3 79.3 Example 4 76.6 Comparative Example 1 76.1

Referring to Table 3, it was found that the speed-up performance of the coin cell of Example 1-4 was improved compared with that of Comparative Example 1.

3) Example 1 and Comparative Example 6

Similar to the above-described rate-limiting performance evaluation methods of Example 1 and Comparative Example 1-4,

And the rate characteristics of the coin cell of Comparative Example 6 were evaluated.

As a result of the evaluation, it was found that the rate-controlling performance of the coin cell of Example 1 was improved as compared with that of Comparative Example 6.

Evaluation example  9: Non-capacity

1) Example 1 and Comparative Example 1-4

The coin cells prepared according to Example 1 and Comparative Example 1-4 were charged and discharged 120 times at a constant current of 1 C rate in a voltage range of 2.5 to 4.6 V relative to lithium metal at a high temperature of 45 ° C. The charging and discharging process was repeated 120 times, and the specific capacity according to the number of cycles was measured and shown in FIG.

As shown in FIG. 13, the lithium battery of Example 1 showed improved non-capacity characteristics as compared with the coin cell of Comparative Example 1-4.

2) Examples 1-2 and Comparative Example 1

The coin cells prepared according to Example 1-2 and Comparative Example 1 were coated with lithium metal

Was charged and discharged 120 times at a constant current of 1 C rate in a voltage range of 2.5 to 4.6 V in contrast. This charging and discharging process was repeated 120 times and the specific capacity according to the number of cycles was measured and shown in FIG.

As shown in FIG. 15, the non-capacitive characteristics of the coin cells of Examples 1 and 2 were improved compared to the case of Comparative Example 1, and the non-capacitive characteristics of the coin cell of Example 1 were improved in the case of Example 2 Compared to the control group.

Evaluation example  10: Adhesion test

A T-peel test (ASTM D1876) was performed on the positive electrode obtained in Example 1 and Comparative Example 1, and the results are shown in FIG.

Referring to Fig. 14, the peel strength of the positive electrode of Example 1 was higher than that of Comparative Example 1. From this, it can be seen that the electrode of Example 1 improves the electrode binding power as compared with that of Comparative Example 1, and as the electrode binding power is improved, the life characteristics of the coin cell employing such anode are improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Of course.

10: core active material 11: carbon nanotube
12: first polymer 13: coating film
20: Lithium battery 22: cathode
23: separator 24: anode
25: cap assembly 26: battery case

Claims (20)

Core active material;
At least one first polymer selected from a fully fluorinated polymer formed on at least a portion of the core active material and a polymer having a fluorine content of 60 to 90 at%; And
A composite cathode active material containing a coating film containing a carbon nanostructure. The method according to claim 1,
Wherein the content of the first polymer is 10 to 700 parts by weight based on 100 parts by weight of the carbon nanostructure. The method according to claim 1,
Wherein the total content of the first polymer and the carbon nanostructure is 0.1 to 30 parts by weight based on 100 parts by weight of the composite cathode active material. The method according to claim 1,
The first polymer may be at least one selected from the group consisting of polytetrafluoroethylene (PTFE), perfluoroalkoxy polymer (PFA), polytetrafluoroethylene-co-hexafluoropropylene (FEP) Fluoroethylene-perfluoroalkyl-methacrylic copolymers, and combinations thereof. The method according to claim 1,
Wherein the carbon nanostructure is a single-walled carbon nanotube, a multi-walled carbon nanotube, or a combination thereof. The method according to claim 1,
Wherein the first polymer or composite cathode active material has a solubility in an organic solvent of 0.1 mg / ml or less. The method according to claim 1,
Wherein the thickness of the coating film is 1 to 200 nm. The method according to claim 1,
Wherein the core active material is selected from the group consisting of overlithiated layered oxides, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide doped with a nonmetal element, lithium nickel manganese oxide doped with a non- A lithium nickel cobalt manganese oxide doped with a non-metallic element, and a combination thereof. The method according to claim 1,
Wherein the core active material is a compound represented by the following Formula 1:
[Chemical Formula 1]
_{yLi [Li 1/3 Me 2} /3] O 2 - (1-y) LiMe'O 2
Wherein 0 < y &lt; 1,
Me is at least one selected from Mn, Mo, W, V, Ti, Zr, Ru, Rh, Pd, Os,
Me 'is at least one selected from among Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg and boron. 10. The method of claim 9,
In Formula 1, Me is a composite cathode active material represented by Formula 2:
(2)
M ' _a M _b Mn _c
M in Formula 2 may be at least one selected from the group consisting of molybdenum (Mo), tungsten (W), vanadium (V), titanium (Ti), zirconium (Zr), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium , Iridium (Ir), and platinum (Pt).
M 'is at least one selected from the group consisting of Ni, Cu, Zn, Co, Cr, Fe and Mg,
0? A? 0.33, 0 <b? 0.33, and a + b + c = 1. The method according to claim 1,
Wherein the core active material is at least one selected from the group consisting of compounds represented by the following Chemical Formulas 3 to 6:
(3)
Li _x Co _{1 - y - z} Ni _y M _z O _{2 - a} X _a
0.9? X? 1.6, 0? Y? 1, 0? Z? 1, 0? A?
X is at least one selected from oxygen (O), fluorine (F), sulfur (S) and phosphorus (P)
M is at least one selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg,
[Chemical Formula 4]
Li _x Mn _{2 - y} M _y O _{4 - a} X _a
X? 1.6, 0? Y? 1, 0? Z? 0.5, 0? A? 1,
X is at least one selected from oxygen (O), fluorine (F), sulfur (S) and phosphorus (P)
M is at least one selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg,
[Chemical Formula 5]
MFePO ₄
In Formula 5, M is at least one selected from the group consisting of Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga, Mg,
(6)
Li _x M _y M ' _z PO _{4 - d} X _d
0.9? X? 1.1, 0? Y? 1, 0? Z? 1, 1.9? X + y + z? 2.1, 0? D? M is at least one selected from the group consisting of Fe, Mn, Ni and Co;
M 'is composed of Mg, Ca, Sr, Ba, Ti, Zr, Nb, Mo, W, Zn, Al, Si, Cr, Zr, Nb, Cu, V, Ti, Zn, Ga, At least one selected from the group; X is at least one selected from the group consisting of S and F. The method according to claim 1,
The core active material
_{Li 1 .18 Ni 0 .17 Co 0} .1 Mn 0 .56 O 2, LiCoO 2, LiFePO 4, LiFe 1 -a Mn a PO 4 (0 <a <1), LiNi 0 .5 Mn 1 .5 O ₄ or LiMnPO ₄ . The method according to claim 1,
Wherein the coating film is in the form of a single film or a multilayer film. The method according to claim 1,
Wherein the coating film comprises a first coating film containing at least one first polymer selected from a completely fluorinated polymer formed on the core active material and a polymer having a fluorine content of 60 to 90 atomic percent and a carbon nanostructure formed on the first coating film And a second coating film. The method according to claim 1,
Wherein the coating film comprises polytetrafluoroethylene and carbon nanotubes. At least one first polymer selected from a completely fluorinated polymer and a polymer having a fluorine content of 60 to 90 atomic% on the core active material; And forming a coating film containing a carbon nanostructure. The method of producing a composite cathode active material according to any one of claims 1 to 15, 17. The method of claim 16,
The step of forming the coating film
A method for producing a composite cathode active material according to a dry method. 18. The method of claim 17,
Wherein the drying method is one selected from the group consisting of a planetary ball milling method, a low speed ball milling method, a high speed ball milling method, a hybridization method and a mechanofusion method. An anode comprising the composite cathode active material according to any one of claims 1 to 15. 20. A lithium battery comprising a positive electrode according to claim 19.

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